1. Field of the Invention
The invention relates to a centralizing device for maintaining a well conduit in a central position with respect to a well bore.
2. Description of the Prior Art
Conduit centralizers, such as casing centralizers, have been employed for almost as long as well casings have been inserted in well bores. The centralizer commonly comprises two axially spaced pairs of ring members which are generally formed from at least two hingedly interconnecting segments to permit the rings to be positioned on the casing in snug but slidable relationship thereto. The axially spaced rings are rigidly connected to opposite ends of outwardly bowed portions of the leaf spring members spaced around the periphery of the rings. The outwardly bowed portions of the leaf springs are proportioned to engage the well bore and to be compressed inwardly by such engagement, thus exerting a centralizing force on the casing to which the centralizer is applied. Normally the centralizer is moved into the well with the casing by a clamping ring which is mounted securely to the exterior of the casing at a position between the two spring connected slidable rings.
Because of the ever increasing depths of modern wells, requiring a large number of casing centralizers to be employed for each well, there has been great emphasis in the well tool industry to minimize the cost of centralizers without in any manner reducing their effectiveness. It has previously been proposed, for example in U.S. Pat. No. 4,088,186 to Callihan et al, to fabricate the pivotally interconnected slidable rings from stampings to minimize the manufacturing costs thereof. The stamping procedure necessarily means that the hinge elements on ends of the segment components of each slidable ring are formed by bending operations on projecting tabs which are well known to produce a wide variation in dimensions of the resulting hinges. Moreover, the application of forces to the hinges can result in a springing of the hinge ends which are not supported or secured in any manner other than the interengagement of the hinges by the hinge pin. It is important that the sliding rings, when assembled, have an internal diameter closely approaching that of a true cylinder, and an internal diameter exceeding the diameter of the casing to which it is to be assembled by only a few thousandths of an inch so that a snug sliding fit of the slidable rings on the casing is achieved. This has not been possible with the stamped components heretofore utilized in the art.